With the ever increasing demand for optical fibers and, therefore, fiber optic connectors, more cost effective designs of connectors are being sought as well as more efficient methods of producing them. Preferably, the new connector designs must be compatible with automated production methods in order to minimize costs and increase the supply of connectors in order to meet the ever increasing demand. Additionally, because the space which is available for the fiber optic cable and connectors is usually limited, the size of the connectors should be minimized to the extent possible while maintaining strength and durability necessary to survive the frequent connects and disconnects from panels and other connectors.
Consequently, a number of optical fiber connectors have been developed in an attempt to meet these design considerations but significant improvement in connector design remains to be realized. For example, three well-known types of fiber optic connectors are the ST ("ST" is a trademark of AT&T), SC, and FC connectors. The ST connector incorporates a bayonet-style fastener which includes a coupling having one or more outwardly extending projections and a rotatable female socket. The female socket has a spiral slot for receiving the projections. The SC type connector has a rectangular cross-section but has components similar to the ST connector, including a ferrule, a collar, a spring, a crimp ring, and a boot. The FC connector has a circular shell similar to the ST connector. The FC also includes a ferrule, a ferrule collar, a spring, a shell, a crimp ring, and an outer housing.
Examples of these three types of connectors are disclosed in U.S. Pat. No. 5,321,784 to Cubukciyan et al. Cubukciyan et al. is directed to a system for manufacturing a variety of fiber optic connectors which are compatible with existing connector formats, including FC, SC, and ST push-pull connectors. The system includes a connector subassembly which is constructed of components common to the FC, SC, and ST connector designs. The connector subassembly includes a ferrule and ferrule collar contained in a connector body, a spring biasing the collar toward the ferrule, a crimp ring for securing the strength members of the fiber optic cable to the connector body, and a boot for strain relief at the crimp location. Several different connector shells are provided for each of the connector formats or types (i.e., FC, SC and ST) and the interior of the shells are adapted to be attached to the single connector body. The Cubukciyan patent discloses that all of the parts in the connector subassembly snap together. While the snap-together feature may minimize parts, it may not result in a rugged, durable connector, especially if the key parts such as the crimp body and housing are made of plastic.
An early FC type connector manufactured by Siecor Corp. of Hickory, N.C., the assignee of the present invention, is shown in FIG. 1. The connector 10 includes, a crimp body 11, a spring 12, a ferrule assembly 13, a coupling nut 14, a bushing 15, and a keying ring 16. The crimp body and the bushing must be milled on a CNC machine which is relatively costly. Additionally, the method of assembly of this connector is not susceptible to automation because the parts cannot be assembled in a top-down or bottom-up fashion. That is, the parts cannot be assembled in a successive fashion in one direction, e.g. by stacking, so that the assembly of this FC connector is not amenable to automated assembly.
A more recent version of the FC connector manufactured by Siecor Corp. is shown in FIG. 2A. This connector includes an extended crimp body 35, a coupling nut 36, a ferrule assembly 37, an outer clip 38, and an inner clip 39. The ferrule assembly is retained in the crimp body by the inner clip 39 while the coupling nut is retained on the extended crimp body between a collar on the extended crimp body and the outer clip 38.
Yet another version of an FC type connector manufactured by Siecor Corp. is shown in FIG. 2B. This connector includes a ferrule assembly 20, an inner clip 21, a spring 22, an extended crimp body 23 having a first end 24 and a second end 25, a coupling nut 26, an outer "C" clip (not shown), and a fiber guide (lead in) tube 28. The ferrule assembly 20 is held inside of the extended crimp body 23 by the inner clip 21 while the coupling nut 26 is slidably mounted on the extended crimp body between the outer "C" clip mounted on the first end 24 of the crimp body and an outwardly extending collar 30 disposed near the second end 25 of the extended crimp body. The particular features of the extended crimp body, specifically the key 31 disposed on the extended crimp body between the second end and the collar as well as one or more notches 33 on the extended crimp body near the first end, require that the crimp body be manufactured on a CNC machine which is more costly and time consuming than parts manufactured on a screw machine having multiple spindles for manufacturing multiple parts at one time. Additionally, because inner and outer clips are used to assemble the ferrule assembly within the extended crimp body and the extended crimp body within the coupling nut, this connector cannot be assembled in bottom-up or top-down fashion.
While more recent connector designs may have less components that the early designs, none of the above designs provide a durable fiber optic connector capable of fully automated assembly. Since large numbers of fiber optic connectors are manufactured every day, the inefficiencies created by assembly processes that are less than fully automated can quickly result in significantly increased fabrication times and fabrication costs.